Lydekkerinidae

{{Short description|Extinct family of temnospondyls}} {{Automatic taxobox | fossil_range = [[Triassic]], {{fossil range|252.3|247.2}} | image = Lyddekerina1db.jpg | image_caption = Life restoration of ''[[Lydekkerina|Lyddekerina huxleyi]]'' | taxon = Lydekkerinidae | authority = Watson, [[1919 in paleontology|1919]] | synonyms = * Deltacephalidae <small>Maryánska and Shishkin, 1996</small> }}

'''Lydekkerinidae''' is a [[Family (taxonomy)|family]] of [[stereospondyl]] [[temnospondyl]]s that lived in the [[Early Triassic]] period. During this time period, lydekkerinids were widely distributed, with putative remains reported from [[Russia]], [[Greenland]], [[India]], [[South Africa]], [[Madagascar]], [[Australia]], and [[Antarctica]].<ref>{{Cite journal |last=Hewison |first=Robin H. |date=1996 |title=The skull of Deltacephalus whitei, a lydekkerinid temnospondyl amphibian from the Lower Triassic of Madagascar |journal=Palaeontology |volume=39 |pages=305–322}}</ref><ref name=":0">{{Cite journal |last1=Shishkin |first1=Mikhail A. |last2=Rubidge |first2=Bruce S. |last3=Kitching |first3=James A. |date=1996-11-29 |title=A new lydekkerinid (Amphibia, Temnospondyli) from the lower Triassic of South Africa: implications for evolution of the early capitosauroid cranial pattern |url=http://dx.doi.org/10.1098/rstb.1996.0147 |journal=Philosophical Transactions of the Royal Society of London. Series B: Biological Sciences |volume=351 |issue=1347 |pages=1635–1659 |doi=10.1098/rstb.1996.0147 |bibcode=1996RSPTB.351.1635S |issn=0962-8436|url-access=subscription }}</ref><ref name="SM00" /><ref name="JDR06">{{cite journal |last=Jeannot |first=A.M. |author2=Damiani, R. |author3=Rubidge, B.S. |year=2006 |title=Cranial anatomy of the Early Triassic stereospondyl ''Lydekkerina huxleyi'' (Tetrapoda: Temnospondyli) and the taxonomy of South African lydekkerinids |journal=Journal of Vertebrate Paleontology |volume=26 |issue=4 |pages=822–838 |doi=10.1671/0272-4634(2006)26[822:CAOTET]2.0.CO;2 |s2cid=86227485 |issn=0272-4634}}</ref><ref>{{Cite journal |last1=WARREN |first1=A. A. |last2=DAMIANI |first2=R. |last3=YATES |first3=A. M. |date=2006-09-04 |title=The South African stereospondyl Lydekkerina huxleyi (Tetrapoda, Temnospondyli) from the Lower Triassic of Australia |url=http://dx.doi.org/10.1017/s0016756806002524 |journal=Geological Magazine |volume=143 |issue=6 |pages=877–886 |doi=10.1017/s0016756806002524 |bibcode=2006GeoM..143..877W |s2cid=13931179 |issn=0016-7568|url-access=subscription }}</ref><ref>{{Cite journal |last1=Gee |first1=Bryan M. |last2=Makovicky |first2=Peter J. |last3=Sidor |first3=Christian A. |date=2021-12-17 |title=Upside down: 'Cryobatrachus' and the lydekkerinid record from Antarctica |url=http://dx.doi.org/10.1017/jpa.2021.115 |journal=Journal of Paleontology |volume=96 |issue=3 |pages=658–683 |doi=10.1017/jpa.2021.115 |s2cid=245312022 |issn=0022-3360|doi-access=free }}</ref> In contrast to most other stereospondyls, lydekkerinids were relatively small-bodied (most with skulls less than 10 cm in length). The [[type genus]] is ''[[Lydekkerina]]'', the namesake of the family and the best-known lydekkerinid.

==Description==

The identification of features shared among lydekkerinids ([[Apomorphy and synapomorphy|synapomorphies]]) necessarily varies depending on which taxa are considered to belong to this group (see further in next section). In the most expansive concept, the family includes the eponymous ''Lydekkerina'' (and junior synonyms like '<nowiki/>''Broomulus''<nowiki/>' and '<nowiki/>''Limnoiketes''<nowiki/>'), ''Eolydekkerina'' from South Africa, ''Deltacephalus'' from Madagascar, ''Luzocephalus'' from Russia and Greenland (which includes the '<nowiki/>''Aquiloniferus''<nowiki/>' of Bjerring (1999),<ref>{{Cite book |last=C. |first=Bjerring, Hans |url=http://worldcat.org/oclc/872235769 |title=Meddelelser om Grønland. a new amphibious tetrapod from the Greenlandic Eotriassic |date=1999 |oclc=872235769}}</ref> which is largely refuted by other workers), ''Chomatobatrachus'' from Australia, and indeterminate records from Antarctica and India ('<nowiki/>''[[Indobenthosuchus]]''<nowiki/>' and '''[[Cryobatrachus]]''<nowiki/>'). However, most previous workers have not considered all of these taxa to be true lydekkerinds;<ref name="JDR06" /> in particular, the affinities of non-South African taxa have been challenged.

For example, Schoch & Milner (2000) considered all nominal lydekkerinids to belong to this family and listed featured like longitudinally oval, unpaired anterior palatal openings, with a pointed posterior end; and a broad and laterally extensive postorbital and prefrontal as synapomorphies.<ref name="SM00" /> Jeannot et al. (2006) considered most nominal lydekkerinids to indeed be lydekkerinids except for ''Deltacephalus'' and the indeterminate records.<ref name="JDR06" /> They list features like a step-shaped contact between the nasal and prefrontal; indentation of anterolateral margin of interpterygoid vacuity; and a straight cheek margin when viewed in occipital view as synapomorphies. Conversely, Hewison (2007) did not consider ''Chomatobatrachus'' or ''Luzocephalus'' to be lydekkerinids and therefore listed a different set of features, such as palatine lacking denticles, but having an elongated postero-mesial process extending behind the most anterior ectopterygoid tooth; ectopterygoid lacking denticles; and septomaxillary with an ornamented roofing portion and an unornamented, plate- like intranarial portion.<ref name=":1">{{Cite book |last=Hewison |first=Robin H. |title=The skull and mandible of the stereospondyl Lydekkerina huxleyi (Tetrapoda: Temnospondyli) from the Lower Triassic of South Africa, and a reappraisal of the family Lydekkerinidae, its origin, taxonomic relationships and phylogenetic importance |publisher=Robin Hewison |year=2007 |location=Somerset |pages=1–80}}</ref> Many of Hewison's features (of which there are more than two dozen) are not synapomorphies but rather are part of a unique combination of features or are [[Plesiomorphy and symplesiomorphy|symplesiomorphies]], and they are not mutually exclusive with the autapomorphies of other workers.

Most recently, it has also been suggested that another small-bodied Early Triassic clade, [[Lapillopsidae]], might nest within Lydekkerinidae, rendering the latter paraphyletic.<ref name=":2">{{Cite journal |last1=Eltink |first1=Estevan |last2=Schoch |first2=Rainer R. |last3=Langer |first3=Max C. |date=2019-04-16 |title=Interrelationships, palaeobiogeography and early evolution of Stereospondylomorpha (Tetrapoda: Temnospondyli) |url=http://dx.doi.org/10.1007/s41513-019-00105-z |journal=Journal of Iberian Geology |volume=45 |issue=2 |pages=251–267 |doi=10.1007/s41513-019-00105-z |s2cid=146595773 |issn=1698-6180|url-access=subscription }}</ref> If so, this would introduce further uncertainty regarding diagnostic features of Lydekkerinidae.

==Classification==

Lydekkerinids are usually classified as basal stereospondyls. Schoch and Milner (2000) placed them in the clade [[Rhytidostea]] along with [[Brachyopoidea|brachyopoids]] and [[Rhytidosteidae|rhytidosteids]],<ref name="SM00">{{cite book |last1=Schoch |first1=Rainer R. |title=Handbuch der Paläoherpetologie |last2=Milner |first2=Andrew R. |publisher=Verlag Dr. Friedrich Pfeil |year=2000 |editor=P. Wellnhofer |volume=3B |location=Munich |pages=1–203 |chapter=3B. Stereospondyli}}</ref> but this broader grouping is not widely employed today given the higher nesting position of brachyopoids and the uncertain position and monophyly of rhytidosteids.<ref name="YW00" /><ref>{{Cite journal |last1=Warren |first1=Anne |last2=Marsicano |first2=Claudia |date=2000-09-25 |title=A phylogeny of the Brachyopoidea (Temnospondyli, Stereospondyli) |url=http://dx.doi.org/10.1671/0272-4634(2000)020[0462:apotbt]2.0.co;2 |journal=Journal of Vertebrate Paleontology |volume=20 |issue=3 |pages=462–483 |doi=10.1671/0272-4634(2000)020[0462:apotbt]2.0.co;2 |s2cid=86107783 |issn=0272-4634|hdl=11336/93649 |hdl-access=free }}</ref><ref name=":3">{{Cite journal |last1=Dias-da-Silva |first1=Sérgio |last2=Marsicano |first2=Claudia |date=2011 |title=Phylogenetic reappraisal of Rhytidosteidae (Stereospondyli: Trematosauria), temnospondyl amphibians from the Permian and Triassic |url=http://dx.doi.org/10.1080/14772019.2010.492664 |journal=Journal of Systematic Palaeontology |volume=9 |issue=2 |pages=305–325 |doi=10.1080/14772019.2010.492664 |s2cid=84569779 |issn=1477-2019|hdl=11336/68471 |hdl-access=free |url-access=subscription }}</ref><ref name=":4">{{Cite journal |last=Schoch |first=Rainer R. |date=2013 |title=The evolution of major temnospondyl clades: an inclusive phylogenetic analysis |url=http://dx.doi.org/10.1080/14772019.2012.699006 |journal=Journal of Systematic Palaeontology |volume=11 |issue=6 |pages=673–705 |doi=10.1080/14772019.2012.699006 |s2cid=83906628 |issn=1477-2019|url-access=subscription }}</ref> Lydekkerinidae was also sometimes historically placed within the largely defunct Rhinesuchoidea<ref>{{Cite book |last=Sherwood |first=Romer, Alfred |url=http://worldcat.org/oclc/253748351 |title=Review of the labyrinthodontia |date=1947 |oclc=253748351}}</ref><ref>{{Cite journal |last=Cosgriff |first=John W. |date=1984 |title=The temnospondyl labyrinthodonts of the earliest Triassic |url=http://dx.doi.org/10.1080/02724634.1984.10011984 |journal=Journal of Vertebrate Paleontology |volume=4 |issue=1 |pages=30–46 |doi=10.1080/02724634.1984.10011984 |issn=0272-4634|url-access=subscription }}</ref> or within the still valid [[Capitosauroidea]] or [[Capitosauria]],<ref name=":0" /> but this too has not been supported by more recent work. Most [[phylogenetic]] studies that sampled only certain nominal lydekkerinids within a larger temnospondyl sample have found lydekkerinids to be [[Paraphyly|paraphyletic]] or [[polyphyletic]].<ref>{{Cite journal |last1=Ruta |first1=Marcello |last2=Pisani |first2=Davide |last3=Lloyd |first3=Graeme T |last4=Benton |first4=Michael J |date=2007-12-22 |title=A supertree of Temnospondyli: cladogenetic patterns in the most species-rich group of early tetrapods |journal=Proceedings of the Royal Society B: Biological Sciences |language=en |volume=274 |issue=1629 |pages=3087–3095 |doi=10.1098/rspb.2007.1250 |issn=0962-8452 |pmc=2293949 |pmid=17925278}}</ref><ref name=":3" /><ref name=":4" /><ref>{{Cite journal |last1=Ruta |first1=Marcello |last2=Jeffery |first2=Jonathan E. |last3=Coates |first3=Michael I. |date=2003-12-07 |title=A supertree of early tetrapods |url=http://dx.doi.org/10.1098/rspb.2003.2524 |journal=Proceedings of the Royal Society of London. Series B: Biological Sciences |volume=270 |issue=1532 |pages=2507–2516 |doi=10.1098/rspb.2003.2524 |pmid=14667343 |pmc=1691537 |issn=0962-8452}}</ref><ref name=":2" /> Furthermore, no complete phylogenetic analysis of all nominal lydekkerinids that would support monophyly in at least a restricted framework has been formally published.<ref>{{Cite journal |last1=Dias-da-Silva |first1=Sergio |last2=Hewison |first2=Robin H. |date=2013 |title=Phylogenetic Analysis and Palaeobiogeography of the Pangaean Lower Triassic Lydekkerinidae (Temnospondyli, Stereospondyli). |url=https://www.researchgate.net/publication/277331798 |journal=73rd Meeting of the Society of Vertebrate Paleontology Abstracts |pages=116 |via=ResearchGate}}</ref> ''Luzocephalus'', which would be the largest of the lydekkerinids with a skull length over 15 cm,<ref>{{Cite journal |last=Shishkin |first=Mikhail A. |date=1980 |title=The Luzocephalidae, a new Triassic labyrinthodont family |journal=Paleontological Journal |volume=14 |pages=88–101}}</ref> has often been found to be more closely related to a family called [[Trematosauridae]], such as in the study by Yates and Warren (2000). ''Chomatobatrachus'' has also been frequently dissociated from other nominal lydekkerinids.<ref name=":0" /><ref name=":1" /> Below is a [[cladogram]] from Yates and Warren (2000) showing the [[polyphyly]]:<ref name=YW00>{{Cite journal | last1 = Yates | first1 = A. M. | last2 = Warren | first2 = A. A. | doi = 10.1111/j.1096-3642.2000.tb00650.x | title = The phylogeny of the 'higher' temnospondyls (Vertebrata: Choanata) and its implications for the monophyly and origins of the Stereospondyli | journal = Zoological Journal of the Linnean Society | volume = 128 | pages = 77–121 | year = 2000 | doi-access = free }}</ref>

{{clade| style=font-size:100%;line-height:100% |label1=[[Stereospondyli]] |1={{clade |1=''[[Peltobatrachus]]'' |2={{clade |1=''[[Lapillopsis]]'' |2={{clade |1=[[Rhinesuchidae]] |2={{clade |label1=[[Capitosauria]] |1={{clade |1=''[[Lydekkerina]]'' |2={{clade |1=''[[Mastodonsaurus]]'' |2={{clade |1=''[[Benthosuchus]]'' |2=[[Capitosauridae]]}} }} }} |label2=[[Trematosauria]] |2={{clade |1={{clade |1=''[[Luzocephalus]]'' |2={{clade |1=''[[Thoosuchus]]'' |2=[[Trematosauridae]]}} }} |2={{clade |1={{clade |1=''[[Almasaurus]]'' |2=''[[Koskinonodon|Buettneria]]''}} |2={{clade |1={{clade |1=''[[Laidleria]]'' |2=[[Plagiosauridae]]}} |2={{clade |1=[[Rhytidosteidae]] |2={{clade |1=''[[Keratobrachyops]]'' |2={{clade |1={{clade |1=''[[Pelorocephalus]]'' |2=''[[Siderops]]''}} |2={{clade |1=''[[Xenobrachyops]]'' |2=''[[Batrachosuchus]]'' }} }} }} }} }} }} }} }} }} }} }} }}

The phylogenetic analysis of Damiani (2001) resulted in a monophyletic Lydekkerinidae, although it was only weakly supported and included what is now recognized as the small-bodied Early Triassic capitosaur ''[[Edingerella|Edingerella madagascariensis]]''. Below is a cladogram from that analysis:<ref name=DRJ01>{{Cite journal | last1 = Damiani | first1 = R. J. | title = A systematic revision and phylogenetic analysis of Triassic mastodonsauroids (Temnospondyli: Stereospondyli) | doi = 10.1111/j.1096-3642.2001.tb00635.x | journal = Zoological Journal of the Linnean Society | volume = 133 | issue = 4 | pages = 379–482 | year = 2001 | doi-access = free }}</ref>

{{clade| style=font-size:100%;line-height:100% |label1=[[Stereospondyli]] |1={{clade |label1=[[Rhinesuchidae]] |1={{clade |1=''[[Uranocentrodon]]'' |2={{clade |1=''[[Rhinesuchus]]'' |2=''[[Rhineceps]]''}} }} |2={{clade |label1='''Lydekkerinidae''' |1={{clade |1=''[[Chomatobatrachus]]'' |2=''[[Lydekkerina]]'' |3={{clade |1=''[[Deltacephalus]]'' |2=''[[Edingerella|"Parotosuchus" madagascarensis]]''}} }} |2={{clade |1=[[Mastodonsauroidea]] |2=[[Trematosauroidea]] }} }} }} }}

==Gallery== <gallery> Eolydekkerina magna.jpg|''[[Eolydekkerina|Eolydekkerina magna]]'', of the [[early Triassic]] of [[South Africa]] Lyddekerina1db.jpg|''[[Lyddekerina|Lyddekerina huxleyi]]'', of the early Triassic of South Africa and Australia Cryobatrachus kitchingi.jpg|''[[Cryobatrachus|Cryobatrachus kitchingi]]'', of the early Triassic of Antarctica </gallery>

==References== <references />

==External links== *[https://web.archive.org/web/20081106101021/http://www.palaeos.com/Vertebrates/Units/160Temnospondyli/300.html#Lydekkerinidae Lydekkerinidae at Palaeos.]

[[Category:Stereospondyli]] [[Category:Triassic temnospondyls]] [[Category:Triassic first appearances]] [[Category:Triassic extinctions]] [[Category:Temnospondyl families]]